WO2020133889A1

WO2020133889A1 - Servo motor power line wiring phase sequence error detection method

Info

Publication number: WO2020133889A1
Application number: PCT/CN2019/087245
Authority: WO
Inventors: 吴迪; 杨凯峰; 齐丹丹; 钱巍
Original assignee: 南京埃斯顿自动化股份有限公司
Priority date: 2018-12-25
Filing date: 2019-05-16
Publication date: 2020-07-02
Also published as: CN109856468B; CN109856468A

Abstract

Disclosed in the present invention is a servo motor power line wiring phase sequence error detection method, comprising: determining maximum output torque Tmax of a servo motor; obtaining a torque observed value TL by means of a disturbance observer; determining whether the torque observed value TL exceeds a detection threshold M; and if the amplitude of load torque TL exceeds the maximum output torque Tmax of a servo system, considering that a motor power line phase sequence is wrong. The present invention implements on-line detection of the servo motor power line wiring phase sequence error; a detection process is automatically completed by a servo driver without additional operation of an operator; and an alarm is given upon detecting an error and the operation of a motor is stopped, thereby preventing high-speed uncontrolled operation of the motor. According to the present invention, the load torque observed value is obtained by means of the disturbance observer, thereby improving detection reliability and real-time performance; and no extra hardware costs is needed, and only a detection algorithm is added to a motor controller such as the servo driver and a frequency converter, so that engineering implementation is facilitated.

Description

Method for detecting wrong phase sequence of servo motor power line connection

Technical field

The invention relates to a method for detecting a wrong phase sequence of a servo motor power line connection, and belongs to the technical field of servo systems.

Background technique

With the widespread application of servo systems in various industries, users have put forward higher requirements for the ease of use and intelligence of the servo system. The reliable fault detection technology of the servo system can improve the safety and ease of use of the system, facilitate troubleshooting, reduce personnel input, and reduce equipment losses.

The servo system consists of two parts: a servo driver and a servo motor, and the two are connected by a cable. During normal operation, the wiring between the servo drive and the servo motor is shown in Figure 1. When the phase sequence of the power cable connection is wrong, the servo motor works abnormally as follows:

(1) When the phase sequence of the two phases of the power line is wrong, the motor will oscillate in forward and reverse directions after starting, and the amplitude of the speed oscillation will gradually decay. After a period of time, the motor stops rotating.

(2) When the phase sequence of the three-phase power line is all wrong, after the motor is started, it accelerates in the direction opposite to the torque command.

The servo motor power line wiring inspection scheme used in the project is roughly divided into two categories. The first category is the offline inspection scheme. After the servo system is started, the operator needs to make the servo drive, frequency converter and other motor controllers run in a specific diagnostic mode Perform the inspection; the second type is the online inspection program. For example, after the servo system is excited, there is no need for additional operations by the operator, no diagnostic procedures and commands, and it can automatically detect the connection of the servo motor power line. During the inspection, the servo system does not need to switch. To diagnostic mode.

The Chinese invention patent "A Method for Correcting the Power Line Phase Sequence of Permanent Magnet Synchronous Motors and Drivers for Electric Vehicles" authorized by the Chinese Patent No. CN1039444778B introduces a method for correcting the phase sequence of power lines for permanent magnet synchronous motors of electric vehicles. The realization method is that the permanent magnet synchronous motor driver passes a small current in a fixed direction to the permanent magnet synchronous motor to rotate the motor. The actual phase sequence of the motor power line connection is judged by the positive and negative directions of the motor rotation, and the rotor electrical angle is collected Perform calibration to allow the motor to run normally. This scheme belongs to the scheme of offline detection, and the realization of this scheme requires that the motor controller already knows the initial angle of the motor in the case of the correct phase sequence connection method of the motor before the detection, otherwise the detection result may be wrong;

The Chinese invention patent entitled "Servo Motor Power Wire Broken Wire Detection Method" with the authorized announcement number CN104242767A introduces a method for detecting the servo motor power wire broken wire. This scheme belongs to the online detection scheme. It is only effective for the case where the motor power line is disconnected in one phase. It cannot detect the disconnection of more than two phases in the three-phase power line, nor can it detect the phase sequence error of the motor power line connection.

Summary of the invention

In view of the deficiencies in the prior art, the present invention provides a detection method for the phase sequence error of the servo motor power line connection. The phase sequence error of the servo motor power line connection is detected online based on the disturbance observer. The detection process is completed by the servo driver itself, without The operator performs additional operations. When a phase sequence error is detected, an alarm is output and the motor is stopped to prevent the motor from running at an uncontrolled speed.

The basic idea and principle of the detection method of the phase sequence error of the servo motor power line connection of the present invention:

There is the following conversion relationship between motor speed and motor output torque:

Where T _e represents the torque output by the servo motor (also the output torque of the servo system), T _L represents the load torque, J _S represents the total rotational inertia of the system, ω represents the motor speed, and t is time.

Assuming that T _max is the maximum torque that the servo system can output, under the conditions of correct application and selection, the following formula always holds:

|T _max |≥|T _L | (2)

When the phase sequence of the power line of the servo motor is wrong, the solution of the feedback link is reversed, thereby forming a positive feedback control, and there are divergent or unstable phenomena such as reverse acceleration or reverse oscillation of the motor. Mathematically, it appears

The difference between T _e and T _e can be seen from formula (1), at this time |T _e |≤|T _L |.

Through the disturbance observer, the load torque T _L can be observed. If the magnitude of the load torque T _L exceeds the maximum torque T _max that the servo system can output, the motor power line phase sequence is considered wrong.

When the servo system is working normally, due to the existence of the non-linear link, there must be torque fluctuations. The torque filtering link can effectively avoid the occurrence of detection misjudgment.

The method for detecting the wrong phase sequence of the servo motor power line connection of the present invention has the following steps:

Step 1. Determine the maximum output torque T _{max of the} servo motor, given the detection threshold M and the detection threshold N (N is a natural number).

In order to prevent false alarms due to detection errors, the detection threshold M is preferably k*T _max , where T _max represents the maximum torque allowed by the servo system and k represents the amplification factor. It is preferable to select 1.15 for k, which can also be adjusted according to the actual situation of the servo system.

Step 2. Detect and obtain the torque observation value T _L through the disturbance observer.

Step 3. Determine whether the torque observation value T _L exceeds the detection threshold value M. If the amplitude of the torque observation value T _{L does} not exceed the detection threshold value M, the test is ended; if the amplitude of the torque observation value T _L exceeds the detection value If the threshold is M, go to step 4.

Step 4. Filter the torque observation value T _L to obtain the filtered torque observation value T _L ′.

Step 5. Determine whether the filtered torque observation value T _L ′ exceeds the detection threshold value M, and if the amplitude of the filtered torque observation value T _L ′ does not exceed the detection threshold value M, end this test. If the amplitude of the torque observation value T _L ′ after filtering exceeds the detection threshold M, it is recorded as an over-detection, and the process returns to step 2 to continue the detection.

Step 6. When the recorded number of over-detections is greater than the detection threshold N, it is determined that the phase sequence of the servo motor power line is wrong, the machine is stopped and an alarm is output, and this test is ended.

It should be noted that in practice, the entire detection process is carried out cyclically. After finishing one detection, the servo driver automatically starts the next detection.

The invention realizes the online detection of the phase sequence error of the power line connection of the servo motor. The detection process is automatically completed by the servo driver without additional operation by the operator. After the error is detected, an alarm is output and the motor is stopped to prevent the motor from running at high speed and uncontrolled. The invention obtains the load torque observation value through the disturbance observer, which improves the detection reliability and real-time performance. No additional hardware cost is required, and only the detection algorithm needs to be added to motor controllers such as servo drives and frequency converters, which is easy to implement in engineering.

BRIEF DESCRIPTION

Figure 1 is the correct schematic diagram of the servo motor power line wiring.

Figure 2 is a schematic diagram of the wiring error of the servo motor power line wiring.

Figure 3 is a block diagram of the servo system circuit.

Figure 4 is a block diagram of the disturbance observer.

Fig. 5 is a graph of motor output torque _Te and load torque.

detailed description

The present invention will be further described in detail below in conjunction with embodiments.

Examples

In the following, one of the three-phase power line phase sequence wrong connection method is taken as an example to elaborate the implementation scheme in detail. The wiring method is shown in Figure 2. The B phase of the motor power line is connected to the U phase of the driver output, the C phase of the motor power line is connected to the V phase of the driver output, and the A phase of the motor power line is connected to the W output of the driver.

As shown in FIG. 3, a given torque command TrqCmd and the load torque observation value T _L output by the disturbance observer are calculated to obtain a torque reference value TrqRef, which is sent to the current command processing module 1, and the current command is calculated through rotation transformation and the like Iqr, which is different from the current feedback Iq to obtain the current deviation; after the current deviation passes through the current loop regulator 2 and the voltage command processing module 3, the voltage command is obtained, and the voltage command is applied to the motor to generate current in the motor; the motor flows through The current is sampled by the current sampling 9, and the sampling result enters the current feedback processing module 7 for proportional conversion, filtering, rotation conversion and other processing, and the current feedback Iq is calculated; the angle sensor 8 installed on the motor sends the angle θ to the disturbance observer 5. The disturbance observer 5 obtains the load torque observation value T _L and the angle θ and the torque reference value TrqRef

The load torque observation value T _{L is} sent to the power line out-of-sequence detection module 6 for processing and judgment to obtain a detection result.

An example of a disturbance observer is shown in Figure 4, where K1 represents the proportional coefficient, K2 represents the integral coefficient, K3 represents the differential coefficient, J _S is the total rotational inertia of the system, and K _t is the torque constant. When J _s has been acquired, the load torque observation value T _L can be obtained.

Step 1. Determine the maximum output torque of the servo motor T _max =300% rated torque, given the detection threshold M=k*T _max , k=1.15, and set the detection threshold N=10.

Step 5. Determine whether the filtered torque observation value T _L ′ exceeds the detection threshold value M, and if the amplitude of the filtered torque observation value T _L ′ does not exceed the detection threshold value M, end this test. If the amplitude of the filtered torque observation value T _L ′ exceeds the detection threshold M, the number of over-detections is recorded, and the process returns to step 2 to continue the detection.

Step 6. When the recorded number of over-detections is greater than the detection threshold N, it is determined that the phase sequence of the servo motor power line is wrong, the machine is stopped and an alarm is output, and this test is ended. In practice, the entire inspection process is carried out cyclically. After one inspection, the servo drive automatically starts the next inspection.

As shown in Figure 5, after the motor excitation is started, the amplitude of the motor electromagnetic torque T _e increases until it is limited to 300% of the rated torque, which means that T _e has reached the maximum torque output T _max and the load torque T _L The amplitude of is obviously more than the maximum torque output T _max , reaching more than 450% of the rated torque, indicating that the motor is in an abnormal operating state, and the phase sequence of the motor power line wiring is judged incorrectly based on this.

Claims

A method for detecting the wrong phase sequence of the servo motor power line connection, the steps are as follows:

Step 1. Determine the maximum output torque T max of the servo motor, given the detection threshold M and the detection threshold N, N is a natural number;

Step 2. Detect and obtain the torque observation value T L through the disturbance observer;

Step 3. Determine whether the torque observation value T L exceeds the detection threshold M;

If the amplitude of the torque observation value TL does not exceed the detection threshold M, the current detection is ended;

If the amplitude of the torque observation value TL exceeds the detection threshold M, go to step 4;

Step 4. Filter the torque observation value T L to obtain the filtered torque observation value T L ′;

Step 5. Determine whether the filtered torque observation value T L ′ exceeds the detection threshold M,

If the amplitude of the torque observation value T L ′ after filtering does not exceed the detection threshold M, this test is ended;

If the amplitude of the torque observation value T L ′ after filtering exceeds the detection threshold M, it is recorded as an over-detection, and return to step 2 to continue the detection;

Step 6. When the recorded number of over-detection is greater than the detection threshold N, it is determined that the phase sequence of the servo motor power line is wrong, the machine is stopped and an alarm is output to end this test.
The method for detecting a wrong phase sequence of a power line connection of a servo motor according to claim 1, wherein the detection threshold M is k*T max , where T max represents the maximum torque allowed by the servo system, and k is a coefficient.